Method for arranging signal points in a quadrature amplitude

Abstract

In a signal point arranging method for use with a quadrature amplitude modulator/demodulator device in which a desired number of signal points are arranged on a rectangular plane, a plurality of grid points are first set such that they are symmetrical with respect to the rectangular coordinate axes of the rectangular plane and arranged at intervals of a unit distance. Next, a plurality of concentric circles with their center at the coordinate origin of the rectangular plane are set, each of the concentric circles having a radius equal to a distance between the coordinate origin and a grid point. Then, a desired number of signal points are arranged on points of intersection of the grid points, the concentric circles beginning with the circle smallest in radius and continuing with circles of increasing radius. As a result, each of the signal points can be arranged as close to the coordinate origin as possible, thus enabling the peak power of modulated signals to be minimized. In addition, since the distance between signal points can be held constant, the S/N characteristic does not vary with the signal points and a constant transmission error rate can be secured. As a result, a signal point arrangement is obtained which enables data transmission at minimum required power, reduces transmission error rate and minimizes the S/N characteristic.